Bacteria in excess of 10(4) colony-forming units per ml (CFU/ml), were isolated from voided urine specimens from 127 (79%) of 160 women, 15-45 years of age, consulting in general practice due to frequency and dysuria. Escherichia coli was the species most frequently isolated, followed by Staphylococcus saprophyticus. Chlamydia trachomatis was isolated from 8 (5%) patients, in 6 of whom greater than 10(4) CFU/ml urine were isolated. A 2-fold titre increase in micro-immunofluorescence antibodies to C. trachomatis was demonstrated in 8 cases, the organism itself being isolated in 1 case only. No viruses were isolated in any of 18 women with negative urine cultures. Proteinuria and/or haematuria was found more frequently in patients with S. saprophyticus than in patients with gram-negative rods. Tests for nitrite indicated bacteriuria in only 58% of the patients with greater than 10(4) CFU/ml urine, which can be partly explained by the fact that S. saprophyticus only occasionally reduces nitrate. Cocci were noted in urine sediment in 75% of patients in whom S. saprophyticus was isolated.